Google the term “buying a triple net asset,” and you'll see plenty of how-to articles on the topic.

However, that information seems to be lacking when it comes to selling a NNN property, which is too bad. The success of an investment isn't only pinpointing the right time to buy, but understanding the right time to sell.

The first issue to consider is exit strategy, something that should be in place when the NNN asset is first acquired. An exit strategy means staying the course, even if demand or market conditions fluctuate over the short term.

However, let's say that it's time to execute that exit strategy. Is it still a good time to sell? Possibly, under the following conditions.

New lease, or long-term lease renewal. If the NNN property tenant just signed or renewed a long-term lease (10 years or longer), investors will likely regard the asset more favorably.

Upgrades. Newer is better, especially when it comes to single tenant, NNN assets. The value of the building and property increases when you and/or the tenant spruce it up.  The value also increases as the tenant upgrades to its franchisor's latest model.

Tenant industry. In the aftermath of the Great Recession, triple net-leased dollar stores were good investments, because they were in demand; everyone wanted to save money. Industry trends can show when it's time to sell.

Improved infrastructure. Is it easier for customers to get to the tenant because of an improved road, new traffic signal or an upgraded sidewalk? More traffic means more sales, with more sales meaning better investment value.

Needless to say, it's important to check with a financial professional or attorney before buying or selling any kind of investment. Just as important is keeping an eye on the indicators demonstrating that the time might be right to dispose of a NNN property.